Conventional systems for anchoring a set of teeth, for example a bridge in the bones of the jaw of the patient, generally require relatively large anchor members which may be sunk in the bones and for which a corresponding cavity in the bone must be fabricated in a substantially freehand manner. The anchor members have a rough upper surface and several discontinuities to facilitate the growth of bone tissue into the implant during the healing process so as to ensconce the implant in the bone.
The spaces between the implant and the surrounding spongiosa are highly prone to infection. Furthermore, since the freehand implantation method makes the size of this space difficult to control, the risk factor for infection is particularly great in earlier systems.
In practice, the conventional anchor has a diameter of about 4 mm so that insertion of the implant using prior art techniques into bones of limited width in the jaw is excluded.
With the aid of a spacer disk, the implant of the prior art systems can be provided with a crown of a set of teeth to be affixed to the jaw, the crown being attached by a screw to the implant. The screw usually must pass through the tooth set and project into the implant. Any discontinuity in the tooth set resulting from the insertion or presence of the screw must be filled. As a consequence, the artificial tooth is generally mounted in a nonremovable manner on the jaw. The tooth set cannot be readily removed, e.g. for cleaning.
Another drawback of earlier systems for mounting a tooth set of a patient on the jaw is that the chewing movements of the patient tend to loosen the screw so that the crown and implant tend to separate and the set of teeth can loosen in the mouth of the patient. To obviate this disadvantage, it is frequently necessary for the dentist or prosthetist to drill through the set of teeth in the region of the screw so that the screw can be tightened. This, of course, requires repair of the damaged set of teeth in the mouth of the patient.